1. Field of the Invention
The present invention relates to a light emitting element, a light emitting element array having a plurality of the light emitting elements, a backlight unit that receives light from the light emitting element array, and a liquid crystal display device including the backlight unit.
2. Description of the Related Art
Conventionally, a flat liquid crystal display device incorporates, for example, a sidelight-type backlight unit that has a light guide plate, and an LED (light emitting element) array which emits light to a side end of the light guide plate (e.g., JP-A-2006-64733). Such a backlight unit includes an LED array having a plurality of LEDs 102, for example, shown in FIGS. 16A to 16C (FIG. 16A is a perspective view, FIG. 16B is a plan view of FIG. 16A, and FIG. 16C is a sectional view taken along the a-a′ line in FIG. 16B).
Usually, as shown in FIGS. 16A to 16C, a light emitting chip 121 is mounted on a bottom portion 131 of a package 126 of the LED (light emitting element) 102 via a slug 122. As shown in FIGS. 17A, 17B (sectional views seen from the same direction as that of FIG. 16C), a portion of the light emitted from the light emitting chip 121 is reflected a plurality of times by an inner wall surface 133 of the package 126, and travels to an opening op of the package 126. For example, FIG. 17A shows an optical path of light (one-dot-one-bar line) that travels in an elevation angle direction, and FIG. 17B shows an optical path of light (two-dot-one-bar line) that travels in a depression angle direction.
Accordingly, besides the light (solid line) that travels from the light emitting chip 121 directly to the opening op of the package 126, the other light (which travels from the light emitting chip 121 to the inner wall surface 133 or the like) also advances to the opening op, and thereby a sufficient amount of light enters the light guide plate through a side end thereof.
However, except for the light that travels from the light emitting chip 121 directly to the opening op of the package 126, the other light is reflected a plurality of times by the inner wall surface 133 of the package 126 before it reaches the opening op. Accordingly, the inner wall surface 133 made of a resin of the package 126 is hit by the light many times, thereby the inner wall surface 133 is deteriorated by the light (light deterioration). Such light deterioration lowers the reflectance of the inner wall surface 133, and reduces the amount of incident light into the light guide plate.